FIG. 2.

Elongating nuclei in cells spreading on a 5-μm line pattern. Maximum intensity projections of NIH 3T3 fibroblasts stably expressing GFP-Lamin A/C (lamina, green) seeded on micro-contact printed 1D lines (represented with dashed yellow lines). The cells were fixed and labeled with Hoechst H33342 (DNA, blue), and Phalloidin (F-actin, magenta) at different time points post-seeding: 10, 20, 60, and 240 min (scale, 5 μm). The nuclear shape changes mirror those of the spreading cells, because the nuclear surface is mechanically coupled to the cell boundary through the intervening cytoplasm. Eventually, the excess area stored in wrinkles and folds disappears, and the nucleus reaches a limiting pill-like shape. At later times, indentations into the lamina surface by stress fibers commonly appear (in the example, fixed at 240 min).